西川红景天nrDNA ITS序列初步研究

Preliminary Studies on ITS Sequences of nrDNA from Rhodiola alsia

[目的]对西川红景天nrDNA ITS序列进行分析,并与cpDNA(叶绿体DNA)trnS-trnG序列和rpl20-rps12序列进行比较,从而初步比较2套植物基因组的进化速率。[方法]采用改良CTAB法从硅胶干燥的西川红景天叶片中提取总DNA,并对nrDNA ITS区进行扩增、纯化、测序,然后与cpDNAtrnS-trnG和rpl20-rps12序列进行比较。[结果]序列比对后得到长度为701 bp的ITS序列,其中变异位点13处,占总序列的1.85%。在13处变异位点中,8处为碱基置换,5处为插入/缺失。(A+T)含量为46.9%,(G+C)含量为53.1%。核苷酸多样性为0.004 27。[结论]西川红景天nrDNA ITS区域较cpDNAtrnS-trnG序列和rpl20-rps12序列保守,进化速率较慢。

[ Objective] The study aimed to analyze the ITS sequences of nrDNA from Rhodiola alisa and investigate the difference of evolution rate between nrDNA and tinS-tmG and rpl20-rps 12 sequences of cpDNA（chloroplast DNA）. [ Method]Total DNA was extracted from silica-dried leaves of R. alsia by using modified CTAB method. With the extracted DNA as template, nrDNA ITS region was amplified, then purified and sequenced. In addition, the yielded ITS sequences were also compared with the known tinS-trnG and rpl20-rps 12 sequences of cpDNA from R. alsia. [ Result ]The ITS sequence of nrDNA from R. alsia was 701 bp in length, of which 13 variable sites were found with a percentage of 1.85%. Of the 13 variable sites, 8 were caused by point mutations, 5 were the results of insertions or deletions. The （A ＋ T） content and （G ＋ C） content were 46.9% and 53.1%, respectively. The nucleotide diversity （n） was 0.004 27. [Conclusion]The ITS region of nrDNA from R. alsia was more conservative and evolved more slowly than the tinS- trnG and rpl20- rps 12 sequences of its cpDNA.